Steed investigates when African leader Sir Wilbuforce Lungi (Andre Dekar) is nearly assassinated during a diplomatic visit to London. Heading to Lungi's homeland, Steed discovers that the person behind the plot is the leader's "trusted" female assistant. Dr. Keel is brought into the proceedings when the villains attempt to infect Lungi with a deadly yellow fever virus. Written by Patrick Campbell, "The Yellow Needle" originally aired June 10, 1961. ~ Hal Erickson, Rovi